Center for Measurement and Analysis of Network Data @ NPS

HICCUPS (Handshake-based Integrity Check of Critical Underlying
Protocol Semantics) is a lightweight extension to TCP that helps end-hosts infer
when their communication is being misinterpreted due to middlebox packet header
modifications.
HICCUPS applies a tamper-evident seal to the TCP 3-way
handshake that is incrementally deployable and cooperative with today's middleboxes.

This web page documents HICCUPS and provides code for our development efforts.
Please contact us for
more information, or if you're interested in hosting a HICCUPS instance
to facilitate development and Internet-wide measurement efforts.

Why:

The modern Internet contains a variety of middleboxes
that operate on network traffic in ways other than traditional IP routing.
Middleboxes are used for a number of reasons: enhancing performance,
enforcing policies, and adding new network features. Examples range from a
large corporate firewall to the wireless router you have at home.

Unfortunately, middleboxes are often hard to setup and configure.
Misconfigurations and out-of-date or non-standard behaviors occur regularly and
in some cases can severely degrade TCP performance. The causes are often
subtle and can be a challenge to diagnose. Even more troubling is the
impact middleboxes have on protocol innovation: any new option, repurposed
field, or otherwise unrecognized behavior is often misunderstood and blocked,
hindering the deployment of new protocols and extensions.